maintenance too low??

I don't know if it applies here, but the lowest monthlies I've seen is when the building has some major income of some sort. Perhaps a doctor's office? Something commercial?

Also, is it possible they just have like a freakish reserve?

some buildings have paid off their mortgage, that will lower the maintenance by 30-50% usually. with some buildings, the maintenance on the first few floors that have "issues" (brick wall view, on top of the boiler, etc) is significantly lower. though not this low.

1158 Fifth's mortgage is only $1,200,000, so not much for the 58 apartments to carry.

Here's how shares are allocated among some of the D-line apartments, all with same plan:

2D 90
5D 120
8D 140
15D 195

That corresponds with what the first buyers would've paid when it went co-op in the 1960s, and of course the ongoing maintenance.

I read an article that said many times a buildings flip taxes, if substantial, can generate revenues that can/may result in lower maint.